''It's being treated as suspicious, but we need to confirm that with the fire investigator.''

It is thought the blaze began near Landfill Rd, she said.

Fire crews are working frantically to dampen hot spots before an expected southerly change.

The area looked good, but there were some concerns, Ms Thorp said.

''There's the odd hot spot where it gets into gorse and flares up.

''We're working really hard to get active fronts out so it doesn't jump the containment lines that we've got at the moment.''

Two helicopters with monsoon buckets were still dousing flames while another was transporting firefighters to different areas.

Fifty firefighters were at the scene, she said.

Detective Inspector Grant Wormald confirmed this afternoon that police would help the Fire Service with their investigation, however conditions meant staff could not get to the area where it was believed the fire began.

"We are hoping to begin a scene examination later today or early tomorrow once the area is accessible, Mr Wormald said.

"It is far too early to say if the fire has been deliberately lit, however, the Rural Fire Service have advised us that it is suspicious."

Helipro base manager Riley Massey said they had had three helicopters in attendance since early this morning.

They would be staying on call over the next couple of days as hot spots were monitored.

"You never know what might happen, with this amount of lovely weather we are having we've just got to be careful."

Residents were evacuated about 2am this morning after the fire began streak up a hill south of Brooklyn and covering 10 hectares on Landfill Rd, just off Happy Valley Rd in Owhiro Bay.

The flames, up to five metres high at times, threatened houses early this morning but firefighters were successful in diverting the blaze away from the area.

Despite the fire, Happy Valley Rd and Owhiro Bay School are open.

About 10-15 households on Rarangi Way were evacuated to Owhiro Bay School in the night, about 30 residents.

Residents were told around 7.15am that they could return to their homes, the annoucement met with applause by those at the Civil Defence evacuation base.

Owhiro Bay resident Lance Shepherd said early this morning wind had not helped emergency services.